Communication instructions Chapter 9
Rockwell Automation Publication 2080-RM001D-EN-E - February 2015 209
MODBUS2LOCPARA data type
The following table describes the MODBUSLOCPARA data type parameters.
Parameter Data type Description
Channel UINT Local Ethernet port number:
• 4 for Micro850 & Micro820 embedded Ethernet port
TriggerType UDINT Message trigger type:
• 0: Msg Triggered Once (when IN goes from False to True)
• 1 to 65535 - Cyclic trigger value in milliseconds. Message triggered periodically when IN is true and the previous message
execution completes.
• Set the value to 1 to trigger messages as quickly as possible.
Cmd USINT Modbus command:
• 01: Read Coil Status (0xxxx)
• 02: Read Input Status (1xxxx)
• 03: Read Holding Registers (4xxxx)
• 04: Read Input Registers (3xxxx)
• 05: Write Single Coil (0xxxx)
• 06: Write Single Register (4xxxx)
• 15: Write Multiple Coils (0xxxx)
• 16: Write Multiple Registers (4xxxx)
• Others: See MODBUS2LOCPARA custom command support
ElementCnt UINT Limits
• For Read Coil/Discrete inputs: 2000 bits
• For Read Register: 125 words
• For Write Coil: 1968 bits
• For Write Register: 123 words
MSG_MODBUS2 message triggering
A Modbus message can be triggered periodically by setting a non-zero value to the
TriggerType parameter. The following table describes what happens when the
TriggerType parameter is used with the MSG_MODBUS2 function block.
Action Results
Message is enabled Trigger timer starts
Trigger timer expires before the message
completes
Message is immediately triggered in the next ladder
scan cycle.
Message completes before the trigger time
expires
Message is triggered when the trigger time expires.
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